arch/unicore32/kernel/dma.c

   1 /*
   2  * linux/arch/unicore32/kernel/dma.c
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
   7  *      Copyright (C) 2001-2010 Guan Xuetao
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/kernel.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/errno.h>
  19 #include <linux/io.h>
  20
  21 #include <asm/system.h>
  22 #include <asm/irq.h>
  23 #include <mach/hardware.h>
  24 #include <mach/dma.h>
  25
  26 struct dma_channel {
  27         char *name;
  28         puv3_dma_prio prio;
  29         void (*irq_handler)(int, void *);
  30         void (*err_handler)(int, void *);
  31         void *data;
  32 };
  33
  34 static struct dma_channel dma_channels[MAX_DMA_CHANNELS];
  35
  36 int puv3_request_dma(char *name, puv3_dma_prio prio,
  37                          void (*irq_handler)(int, void *),
  38                          void (*err_handler)(int, void *),
  39                          void *data)
  40 {
  41         unsigned long flags;
  42         int i, found = 0;
  43
  44         /* basic sanity checks */
  45         if (!name)
  46                 return -EINVAL;
  47
  48         local_irq_save(flags);
  49
  50         do {
  51                 /* try grabbing a DMA channel with the requested priority */
  52                 for (i = 0; i < MAX_DMA_CHANNELS; i++) {
  53                         if ((dma_channels[i].prio == prio) &&
  54                             !dma_channels[i].name) {
  55                                 found = 1;
  56                                 break;
  57                         }
  58                 }
  59                 /* if requested prio group is full, try a hier priority */
  60         } while (!found && prio--);
  61
  62         if (found) {
  63                 dma_channels[i].name = name;
  64                 dma_channels[i].irq_handler = irq_handler;
  65                 dma_channels[i].err_handler = err_handler;
  66                 dma_channels[i].data = data;
  67         } else {
  68                 printk(KERN_WARNING "No more available DMA channels for %s\n",
  69                                 name);
  70                 i = -ENODEV;
  71         }
  72
  73         local_irq_restore(flags);
  74         return i;
  75 }
  76 EXPORT_SYMBOL(puv3_request_dma);
  77
  78 void puv3_free_dma(int dma_ch)
  79 {
  80         unsigned long flags;
  81
  82         if (!dma_channels[dma_ch].name) {
  83                 printk(KERN_CRIT
  84                         "%s: trying to free channel %d which is already freed\n",
  85                         __func__, dma_ch);
  86                 return;
  87         }
  88
  89         local_irq_save(flags);
  90         dma_channels[dma_ch].name = NULL;
  91         dma_channels[dma_ch].err_handler = NULL;
  92         local_irq_restore(flags);
  93 }
  94 EXPORT_SYMBOL(puv3_free_dma);
  95
  96 static irqreturn_t dma_irq_handler(int irq, void *dev_id)
  97 {
  98         int i, dint;
  99
 100         dint = readl(DMAC_ITCSR);
 101         for (i = 0; i < MAX_DMA_CHANNELS; i++) {
 102                 if (dint & DMAC_CHANNEL(i)) {
 103                         struct dma_channel *channel = &dma_channels[i];
 104
 105                         /* Clear TC interrupt of channel i */
 106                         writel(DMAC_CHANNEL(i), DMAC_ITCCR);
 107                         writel(0, DMAC_ITCCR);
 108
 109                         if (channel->name && channel->irq_handler) {
 110                                 channel->irq_handler(i, channel->data);
 111                         } else {
 112                                 /*
 113                                  * IRQ for an unregistered DMA channel:
 114                                  * let's clear the interrupts and disable it.
 115                                  */
 116                                 printk(KERN_WARNING "spurious IRQ for"
 117                                                 " DMA channel %d\n", i);
 118                         }
 119                 }
 120         }
 121         return IRQ_HANDLED;
 122 }
 123
 124 static irqreturn_t dma_err_handler(int irq, void *dev_id)
 125 {
 126         int i, dint;
 127
 128         dint = readl(DMAC_IESR);
 129         for (i = 0; i < MAX_DMA_CHANNELS; i++) {
 130                 if (dint & DMAC_CHANNEL(i)) {
 131                         struct dma_channel *channel = &dma_channels[i];
 132
 133                         /* Clear Err interrupt of channel i */
 134                         writel(DMAC_CHANNEL(i), DMAC_IECR);
 135                         writel(0, DMAC_IECR);
 136
 137                         if (channel->name && channel->err_handler) {
 138                                 channel->err_handler(i, channel->data);
 139                         } else {
 140                                 /*
 141                                  * IRQ for an unregistered DMA channel:
 142                                  * let's clear the interrupts and disable it.
 143                                  */
 144                                 printk(KERN_WARNING "spurious IRQ for"
 145                                                 " DMA channel %d\n", i);
 146                         }
 147                 }
 148         }
 149         return IRQ_HANDLED;
 150 }
 151
 152 int __init puv3_init_dma(void)
 153 {
 154         int i, ret;
 155
 156         /* dma channel priorities on v8 processors:
 157          * ch 0 - 1  <--> (0) DMA_PRIO_HIGH
 158          * ch 2 - 3  <--> (1) DMA_PRIO_MEDIUM
 159          * ch 4 - 5  <--> (2) DMA_PRIO_LOW
 160          */
 161         for (i = 0; i < MAX_DMA_CHANNELS; i++) {
 162                 puv3_stop_dma(i);
 163                 dma_channels[i].name = NULL;
 164                 dma_channels[i].prio = min((i & 0x7) >> 1, DMA_PRIO_LOW);
 165         }
 166
 167         ret = request_irq(IRQ_DMA, dma_irq_handler, 0, "DMA", NULL);
 168         if (ret) {
 169                 printk(KERN_CRIT "Can't register IRQ for DMA\n");
 170                 return ret;
 171         }
 172
 173         ret = request_irq(IRQ_DMAERR, dma_err_handler, 0, "DMAERR", NULL);
 174         if (ret) {
 175                 printk(KERN_CRIT "Can't register IRQ for DMAERR\n");
 176                 free_irq(IRQ_DMA, "DMA");
 177                 return ret;
 178         }
 179
 180         return 0;
 181 }
 182
 183 postcore_initcall(puv3_init_dma);